Conventionally, ion implanters are utilized to place a specified quantity of dopants or impurities within workpieces or semiconductor wafers. In a typical ion implantation system, a dopant material is ionized and accelerated, therein generating a beam of ions. The ion beam is directed at a surface of the semiconductor wafer to implant ions into the wafer, wherein the ions penetrate the surface of the wafer and form regions of desired conductivity therein. For example, ion implantation has particular use in the fabrication of transistors in semiconductor workpieces. A typical ion implanter comprises an ion source for generating the ion beam, a beamline assembly having a mass analysis apparatus for directing and/or filtering (e.g., mass resolving) ions within the beam, and a target chamber containing one or more wafers or workpieces to be treated.
Various types of ion implanters allow respectively varied dosages and energies of ions to be implanted, based on the desired characteristics to be achieved within the workpiece. For example, high-current ion implanters are typically used for high dose implants, and medium-current to low-current ion implanters are utilized for lower dose applications. An energy of the ions can further vary, wherein the energy generally determines the depth to which the ions are implanted within the workpiece, such as to control junction depths in semiconductor devices. Typically, low- to medium-current implanters have a substantial length of travel of the ion beam (also called the beamline of the implanter) before it impacts the workpiece. High-current implanters, however, typically have a much shorter beamline due, at least in part, to the low energies associated with the ion beam, wherein the high-current ion beams tend to lose coherence with longer beamlines.
The ion beam can be stationary, wherein the workpiece is scanned through the stationary beam during implantation. Such a scanning of the workpiece often requires a complex architecture for uniformly translating the workpiece through the stationary ion beam. One alternative to only translating the workpiece is to scan or dither the ion beam in one direction while translating the workpiece in an approximately orthogonal direction. An electromagnet is typically used to alter the path of the ion beam in a controlled manner. However, such a scanner magnet often inhabits a significant portion of real estate along the beamline. Furthermore, in the case of a scanned ion beam, there is often a greater need to focus the ion beam to provide optimal scanning of the beam. However, since the scanner magnet consumes a great deal of beamline length, the implementation of such focusing magnets or optics is conventionally limited.